Agriculture officials said that bean sprouts grown in one organic farm between Hamburg and Hanover were the likely cause of the illness.

Hospital authorities said blood supplies were running low and staff were exhausted and working round-the-clock, with the northern cities of Hamburg and Bremen the worst affected.

“They [the doctors] voluntarily come in on weekends and even sleep here,” Oliver Grieve, a spokesman for the Kiel University hospital in northern Germany told Spiegel Online.

Hamburg’s health minister, Cornelia Prüfer-Storcks, told a news conference the city was considering bringing doctors out of retirement. “We want to discuss with doctors about whether those who recently retired can be reactivated,” she said.

Patients with less serious illnesses are now being moved to nearby hospitals and operations for non-threatening diseases are being postponed.

A spokesman for Regio Clinics, the largest private hospital in the state of Schleswig Holstein, told Reuters: “All the hospitals in the region are pushing their limits. We can handle it but some of our patients have to be sent to other hospitals, especially those with HUS [haemolytic uraemic syndrome] or needing dialysis.”

Extra nurses are being recruited from southern Germany to plug the gaps.

Meanwhile patients have described “horrendous” conditions in some hospitals. One said poor hygiene standards were contributing to the problem.

“All of us had diarrhoea and there was only one bathroom each for men and women, it was a complete mess,” Nicoletta Pabst told the Associated Press. “If I hadn’t been sick with E coli by then, I probably would have picked it up over there.”

She said she had waited three hours to be seen before being sent home, apparently because her blood levels did not indicate that she had kidney failure. Her condition deteriorated and she had to call an ambulance the next morning, she said. She was hospitalised for a week at a different hospital.

Despite the increase in the death toll, authorities said the number of new cases had started to decline.

Meanwhile health inspectors continue testing samples from a restaurant in the northern city of Lübeck.

Tucked away in the cellars of the city’s old town, the Kartoffel Keller became the focus of investigations over the weekend after a local newspaper revealed that up to 17 people who had eaten at the restaurant were infected with E coli, among them tourists from Denmark and a group of German civil servants. Two are seriously ill and a 47-year-old woman died.

The Kartoffel Keller is still open for business as officials from Germany’s disease control authority, the Robert Koch Institute, are poised to release the results of samples taken from the kitchen of the restaurant.

“We’ve taken salad off the menu and put up an official notice on the door to reassure customers that the food is safe to eat,” said the owner, Joachim Berger.

“We’ve got nothing to hide,” he added. “So far all the tests have come up negative. But the guests are staying away.”

But one journalist, Oliver Vogt, said locals were deliberately defying the hysteria.

“People are coming as a show of support,” he said. “This is one of the best-loved restaurants here in Lübeck.”

Just around the corner, the waiter at Lübeck’s only vegetarian cafe had a very different view. “They [Kartoffel Keller] have hit rock bottom,” he said. “You can lose your reputation so fast. It’s not so easy to get it back.”